wisski-cloud-distillery/internal/config/read.go
2022-11-23 15:27:58 +01:00

61 lines
1.6 KiB
Go

package config
import (
"io"
"reflect"
"github.com/FAU-CDI/wisski-distillery/pkg/environment"
"github.com/FAU-CDI/wisski-distillery/pkg/envreader"
"github.com/FAU-CDI/wisski-distillery/pkg/stringparser"
"github.com/pkg/errors"
)
// Unmarshal updates this configuration from the provided [io.Reader].
//
// Data is read using the [envreader.ReadAll] method, see the appropriate documentation for the file format.
//
// The `env` and `parser` reflect tags of the [Config] struct determine the keys to read from, and the types to expect.
// When a key is missing, it is set to the default value.
//
// See also [stringparser.Parse].
func (config *Config) Unmarshal(env environment.Environment, src io.Reader) error {
// read all the values!
values, err := envreader.ReadAll(src)
if err != nil {
return err
}
vConfig := reflect.ValueOf(config).Elem()
tConfig := vConfig.Type()
// iterate over the types
numValues := tConfig.NumField()
for i := 0; i < numValues; i++ {
tField := tConfig.Field(i)
vField := vConfig.FieldByName(tField.Name)
tEnv := tField.Tag.Get("env")
tDefault := tField.Tag.Get("default")
tParser := tField.Tag.Get("parser")
// skip it if it isn't loaded!
if tEnv == "" {
continue
}
// read the value with a default
value, ok := values[tEnv]
if !ok || value == "" {
if tDefault != "" {
value = tDefault
}
}
// parse the value!
if err := stringparser.Parse(env, tParser, value, vField); err != nil {
return errors.Errorf("Config.Unmarshal: Setting %q, Parser %q: %s", tEnv, tParser, err)
}
}
return nil
}